Michael Kovac/Getty Images for The Elton John AIDS Foundation(LAKE FOREST, Calif.) -- Pastor Rick Warren, the leader of Saddleback Church, one of the largest mega-churches in the country, and author of The Purpose Driven Life, plans to return to the pulpit Saturday for the first time since his son's suicide in April.

The sermon he is scheduled to preach Saturday and again on Sunday is the first of a series titled, "How to Get Through What You're Going Through," which, "will show you how the Bible can bring you comfort and encouragement," according to a statement from the church.

The first service is scheduled to start at 4:30 p.m. PT (7:30 p.m. ET) Saturday and will be streamed live on the church's website, saddleback.com.

Warren's son Matthew committed suicide in early April after what the pastor said was a lifelong battle with mental illness.

"No words can express the anguished grief we feel right now," Warren wrote April 6 in a letter to his 20,000-strong congregation. "Our youngest son, Matthew, age 27, and a lifelong member of Saddleback, died today."

The evangelist, who gained international fame for his bestseller, The Purpose Driven Life, remembered his son in the letter as "an incredibly kind, gentle, and compassionate man.

"But only those closest knew that he struggled from birth with mental illness, dark holes of depression, and even suicidal thoughts," Warren wrote. "In spite of America's best doctors, meds, counselors and prayers for healing, the torture of mental illness never subsided."

After a "fun evening" as a family, Warren said his son took his life "in a momentary wave of despair at his home."

Warren said he marveled at his son's courage to keep on living in his darkest moments despite his pain.

"I'll never forget how, many years ago, after another approach had failed to give relief, Matthew said, 'Dad, I know I'm going to heaven. Why can't I just die and end this pain?'" Warren wrote. "But he kept going for another decade."

Pastor Rick Warren's Church

Warren grew his Saddleback Church from humble beginnings into a powerhouse ministry.

The church started as a dream for "a place where the hurting, the depressed, the confused can find love, acceptance, help, hope, forgiveness and encouragement," according to the Saddleback Church website.

Since Warren's first public service on Easter Sunday in 1980, Saddleback Church has grown into a church with more than 200 ministries.

In his 1995 book, The Purpose Driven Church, Warren shared the principles that led to the success of Saddleback.

His follow-up book in 2002, The Purpose Driven Life, catapulted him into the world spotlight.

"The history of this idea -- 'purpose driven' -- is not something I thought up in the first place," Warren told ABC News in 2007. "There have been hundreds of books throughout history that talked about worship, fellowship, discipleship, ministry and evangelism."

The book began with a simple premise: It's not about you.

It was a hit -- and has been translated into dozens of languages and has sold tens of millions of copies.

According to the Saddleback website, The Purpose Driven Life is the best-selling non-fiction hardback book in history.